(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2Fcouplers%2Fcoupler_top.jpg&hash=4473353cb16cc338c849a3b4b181fd569ee426d5)
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2Fcouplers%2Fexploded1.jpg&hash=9809caa0dc4f3d87502487bd7ce33a237e2d3514)
Ray's post on changing scales inspired me. He wanted to go bigger, and that certainly has it's challenges. I, however, decided to try going smaller.
I wanted to see how small I could make a working coupler. Trip pin, knuckle, draft gear and all. At first, I was going to simulate the draft gear action with a spring... but then I thought: why not make the draft gear too?
I have been experimenting with using a cat whisker to trigger the trip pin. Unfortunately, they are very easy to lose, and my cat isn't very happy with me right now.
More photos here: http://burlrice.com/couplers/ (http://burlrice.com/couplers/)
And before anyone asks, here's my scale:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2Fcouplers%2Fscale.jpg&hash=1d4d75b5dafc805f203bd25557feabdf02b75815)
Hi Burl, Welcome to the forums. Nice work, but you'l have to knuckle down about a couple things if you want to be taken seriously ;D
How about a few words how you did it.
We need to change the name of this place to The Comedy Forum! -- Russ
When I first started making my own couplers, I was having a pattern made by Shapeways in brass. I was sending these to a foundry, where it was duplicated in the investment casting process. After a while, when I looked at how much I was ordering from the foundry, I realized it would be cheaper for me to do the wax injecting myself. I have several years experience in resin casting, so the transition was pretty smooth. I bought my own wax injector, a couple different flavors of wax, and started experimenting with platinum based RTV (all the Tin-cure RTVs I had any experience with were too soft). It didn't take long before I was successful.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_Coupler%2Fwax2.jpg&hash=36105ac5fd262f5fcb6de04a2271dfd1c4ed1e98)
My first iteration of this coupler included the centersill as a cast piece:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_Coupler%2Fbrass1.jpg&hash=241d40f8d26a78faf40c3eaa145f09ba623058ae)
After running a few, I could see it wasn't cost effective. I was looking at $10-$12 for each centersill. I also intended to attach the bottom plate with screws. I was not thrilled with the idea of drilling and tapping all those tiny holes, but I couldn't think of anything better. I also did not have a good answer for replicating the draft gear mechanism.
Then the light bulb came on: photoetch. It would require soldering, but I figured I could silver solder the front & rear draft lugs, and the striker plate. Then I could assemble the whole thing and solder the bottom plate on with a lower temp (silver-bearing) solder. It worked acceptably, but I can see after making one up, I need to tweak the fit of some things. Its hard to calculate exactly how the photoetched parts will bend, and a few thousands of an inch makes a difference. And the price came way down - like $2 each.
In my next revision, the striker plate and the front draft lugs will be once piece. They are designed to lock into the centersill when its folded, so no need for a clamping mechanism for soldering. I'm also going to try using .032" rivets to hold the bottom plate in place for soldering. Will post more photos as I progress.
Stunning quality!
And clever. -- Russ
Jewel like work. The humor of the illustration of the scale you work in will make you fit in well with this group.
I have decided to rework my trip pin, and see if I can make it operable. My first revision required the pin to be manually pushed up from beneath. If this revision succeeds, it will be operable by a cut lever.
Here's a 3d rendering:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_Coupler%2Fcoupler9_trip_pin.jpg&hash=f222427736218ca744aa6e99eed33666b4ce6866)
And here are the patterns ready for molding:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_Coupler%2Ftrip_pin_pattern.jpg&hash=815e3b44ff999df4da40bf936f2a0aac303cb78c)
I got distracted last week with some unexpected dental work, but have gotten back to wax casting. Here's the latest batch about to be sent off to the foundry:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_Coupler%2Fwax3.jpg&hash=85977980bcc6d770b69457c6ccca576d0a7e7c1b)
These will be exciting to see assembled!
If this works well are these couplers you are considering offering for sale?
Those turned out beautifully. -- Russ
Bill: If it works, AND I can keep the price reasonable, yes.